1. Field of the Invention
This invention relates in general to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, this invention involves a hydraulic coupling having a pressure-equalizing passage and valve in the female coupler body, allowing sea water to flow into the annulus between the female and male coupling members.
2. Description of the Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with sealed fluid passageways connected therebetween. The female member generally is a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore seals and slidingly engages the male member of the coupling. The male member includes a cylindrical portion at one end having an outer diameter approximately equal to the diameter of the large bore of the female member of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, accordingly to various embodiments of the device, fluid flow is established between the male and female members. Couplings of this type are shown in U.S. Pat. No. 4,694,859 to Robert E. Smith III, and other patents owned by National Coupling Company, Inc. of Stafford, Tex.
In undersea drilling and production applications, the male member of the coupling may be connected to a manifold plate or other securement at a sub-sea location at the inside or outside of the well bore. In many cases, the male members are positioned so that the end or leading face of each member faces up from the sea floor. The female members, which also may be secured to a manifold plate, are moved into position over the male members and then lowered onto the male members by a diver or sub-sea vehicle. When the female members are positioned on the male members, hydraulic fluid flow typically is from the female member to the male member of each coupling. In some cases, only the female member of the coupling has a poppet valve.
The poppet valve typically includes a conical valve face which seats, in the closed position, against the valve seat of the coupling member. The poppet valve opens to allow fluid flow, and closes against the valve seat within the bore to arrest the flow. Generally, the poppet valve is spring biased to the closed position. The valve may include a valve actuator which may be a nose or stem extending from the apex of the valve face along the longitudinal axis of the poppet valve.
Undersea hydraulic couplings of the foregoing type are connected and disconnected while sub-sea. In emergency situations, for example, storms, hurricanes, etc., the coupling members must be quickly disconnected and one of the members, typically the female member, removed from the sub-sea location. When the male member is withdrawn from the large central bore of the female member, there is a resulting low pressure area or vacuum created within the bore. When the end face of the male member passes the mid point of the elastomeric seal in the bore of the female member, the seal no longer has the outer wall of the male member to help retain the seal in its grove. At this point, the pull of the vacuum and the hydraulic pressure of sea water trying to get past the elastomeric seal may implode the seal out of the grove and into the annulus between the male and female members. The vacuum also increases the difficulty of manually disengaging the male member from the female member. This resistance to disengagement due to the vacuum is magnified when multiple couplings and manifold plates are disengaged.